It was in 1759 that Alessandro Volta established that the twitching of frog legs, observed ten years earlier by Luigi Galvani, was due to an electric current flow. It was probably inevitable that electric current would be applied to humans to accomplish some therapeutic result. A modern application is found in the "pace maker" device which stimulates and controls action of the user's heart muscle. In that application, the function is to induce to action to a muscle that might not otherwise contract. Electrical stimulus can also be used to strengthen or "tone" specific muscles by causing them to contract forcefully, and then to relax, and to repeat that cycle over and over in an exercise program.
One of the most important uses for electrical stimulus in muscle exercise is the strengthening of the puboccygeous and related muscles. Those muscles are disposed in the lower pelvic region of humans, in the vicinity of the bladder and rectum. These muscles are important in control of urinary and fecal discharges, and in maintaining the relative positions of the several organs in the lower pelvic region. A common symptom, indicating inadequate strength in the primary muscle of the group, the puboccygeous, is incontinence in stressful circumstances. Medical research statisticions estimate that thirty percent of the adult female population, and sixty percent of post menopausal women suffer from lack of urinary control. Males, too, have this problem.
A cure for most sufferers can be had by strengthening the muscles of the group in an exercise program. The several muscles can be flexed and relaxed voluntarily whereby the muscles are strengthened in an exercise program involving no more than periodic, voluntary, repetitive contraction of the muscles. However, as in the case of any muscle development effort, it is preferred to increase the intensity of exercise with time, at a rate that is a function of the exerciser's age and weight and starting physical condition.
Intensity is a function of contraction force, duration of contraction, frequency, and number of contractions. Except for number of contractions in each exercise session, regulation of intensity in an exercise program that lasts for a period of several months is not possible when contraction is accomplished voluntarily. As a consequence, physicians who treat incontinence, or otherwise supervise a "p.c." muscle exercise program, prefer that contractions be electrically induced.